How Do Cells Keep Us Healthy?

Cell Membrane

The main function of a cell membrane is to determine what to let into the cell and what to let out.

The three ways molecules can get into a cell is by some form of diffusion, by cell signaling, or by both.

The phospholipid bilayer serves as a semi permeable barrier; it is the main component of the membrane

The size and polarity of a molecule determines if they can enter or exit the cell

  • This a layer of phosphates and lipids
  • The tails of a phospholipid are hydrophobic and they are attracted to each other, facing inward.
  • The heads of a phospholipid are hydrophilic and they are attracted to water, facing outward.
  • Cholesterol is utilized to keep the tails from tangling and to stabilize the membrane
  • Glycoprotein and glycolipids receive and transmit signals to other cells
  • Peripheral proteins let the molecule through the membrane halfway

Transport

Active Transport

Passive Transport

Moving substances from a low concentration to a high concentration

Against the concentration gradient

Energy is needed for this (ATP used)

Transport Protein is used

Moving substances from a high concentration to a low concentration

Along the concentration gradient

There is no energy needed for this (No ATP)

Two Types: Simple Diffusion and Facilitated Diffusion

Simple Diffusion: Does not require

Facilitated Diffusion: Using a channel protein

Osmosis

Nonpolar and small

moves through the cell membrane easily,

O2 and CO2

Uses a channel protein to move through the cell membrane

Large and polar

Glucose, ions

Osmosis is defined as the movement of water either into or out of a cell.

Isotonic

Hypertonic

Hypotonic

  • The rate of water molecules moving into the cells is greater than water moving out of cells
  • The plant cell swells and the animal cell can burst
  • Plant Cell: Turgid, Animal Cell: Lysed
  • Turgor Pressure
  • The rate of water molecules moving into the cells is less than water moving out of cells
  • The plant cell shrinks and the animal cell shrivels up
  • Plant Cell: Plasmolysed, Animal Cell: Crenated
  • The rate of water molecules moving into the cells is the same as the water moving out of cells
  • The plant cell and animal cells exhibit little to no difference
  • Plant Cell: Normal, Animal Cell: Normal

Endocytosis

Exocytosis

Sodium Potassium Pump

Active transport (moving against the concentration gradient)

Transports three Na+ to the outside of the cell for the transport of every two K+ ions to the inside

Endocytosis engulfs large particles too large to come in through regular transport using vesicle transport

Endocytosis requires a cell receptor (glycolipid/glycoprotein)

Viruses can move in by imitating a human cell and binding to the receptor

Exocytosis occurs when cells want to get rid/release something.

Exocytosis also requires a glycoprotein/glycolipid as a signal to get out of the cell

Viruses can exit the cell after replicating through exocytosis

Type 2 Diabetes

Type 1 Diabetes

Autoimmune distance: immune system attacks pancreas cells that produce insulin

Without insulin, glucose doesn’t get into the cells and accumulates in the blood

Treatment: Insulin injections, food choices, physical activity, controlled blood pressure and cholesterol

Insulin levels low, glucose levels high

Without the proper signals, glucose cannot get into the cells and accumulates in the blood

Insulin levels high, glucose levels high

Produce insulin but the receptors on the cells don’t bind or respond to the binding

Treatment: Medicines to reduce blood sugar, food choices, exercise, controlled BP and cholesterol